The present invention relates to apparatuses for producing information from a record disc such as in video disc players.
Such reproducing apparatuses are generally in an almost closed structure in order to protect a record disc under a reproducing operation from foreign materials such as dust particles. Referring particularly to a video disc, it is received or stored in a protective sleeve or a caddy so that an operator does not touch the disc with his or her fingers to spoil the recorded surface of the disc. For reproduction, the disc which has been stored in the protective sleeve, is inserted into an insertion slot of a video disc player, and withdrawal of the protective cover causes the video disc player to be loaded with the video disc.
Record discs such as video discs are made principally of vinyl chloride and have a poor heat-resistant capability. Since the softening temperature of vinyl chloride is comparatively low, the permissible upper temperature for a video disc for the CED system is set for 45.degree. C. Meanwhile, the reproducing apparatus is provided with an electronic circuit for processing an electric signal obtained from a record disc and the inner temperature of the apparatus may be substantially increased due to heat generated by the electronic circuit, particularly by the power supply section of the electric circuit. When the disc is placed on the turntable of the reproducing apparatus having been made ready for a reproducing operation and the disc is rotating along with the turntable, air in the vicinity of the rotating turntable and the disc is moved, thereby suppressing a local temperature rise within the reproducing apparatus, and therefore the disc suffers from almost no adverse effect of the above-mentioned heat generated by the electronic circuit. However, when the disc in the reproducing apparatus having been made ready for a reproducing operation is in a stand-by state for a reproduction (or a play) or for a repeated reproduction or is in a state in which the disc is prepared for a withdrawal after a play has been finished, the disc stands still, being on the turntable or being carried by a disc holder over the turntable which is also standing still. If, for some reason, the disc is not withdrawn or not re-played for a long time after a play of the disc has been finished or after the disc is inserted into the reproducing apparatus through the insertion slot, or if the inserted disc is not played for a long time, the disc will be left stationary (not rotated) for a long time in the above-mentioned state in the reproducing apparatus. As a result, a local temperature rise will take place in the apparatus, which may cause the temperature in the vicinity of the disc in the apparatus to exceed the permissible upper temperature for the disc.
When the disc is subjected to a temperature higher than the permissible upper temperature, it suffers from disc warp or potato chip warp or other undesirable deformation. This deformation of the disc makes it impossible for a pickup of the reproducing apparatus to properly trace the record tracks of the disc and therefore normal reproduction of information becomes impossible. Especially in an apparatus wherein the diameter of the turntable is smaller than that of the disc, deformation of the disc is more serious. For preventing such deformation, it is necessary to suppress the temperature rise by the electronic circuit. Possible countermeasures against the local temperature rise may be as follows:
(1) Installing a ventilation fan for cooling effect by the open air; PA1 (2) Installing a circulation fan to average the local temperature rise; and PA1 (3) Lowering the power consumption of the electronic circuit, particularly of its power supply section to limit heat generation.
The measure (1) is not suitable to a player which is intolerant of dust and also brings about an increase of cost due to provision of the ventilation fan. The measure (2) also brings about an increase of cost because of the provision of the circulation fan. The measure (3) appears the better than the others, but a certain minimum amount of electric power is needed to operate the apparatus and inclusion of a certain number of heat generating components is inevitable. Accordingly, it is most difficult to completely prevent the above described warp or deformation by the measure (3).